In the diagnosis of various medical conditions, it is often useful to examine soft tissues and/or blood flow within the body to show structural details of organs and blood vessels in these organs. Multiple studies have demonstrated increased vascularity (blood flow) in many tumors relative to that of normal tissue, and multiple attempts have been made to depict these differences in vascularity using ultrasonic imaging.
As well-known to those of ordinary skill, a standard real-time two-dimensional (2D) ultrasound scan typically entails the following. Referring to FIG. 1, an operator holds a transducer 105 in one position relative to a volume of material, e.g., human tissue in a patient 120. The transducer 105 is sometimes referred to as a scan head; it commonly has an essentially linear, one-dimensional (1D) shape, although scan heads of round or other shapes are also known, and emits a beam of ultrasound energy toward the material in a patient 120. The ultrasound energy is reflected from the material and detected by the scan head 105, which generates data signals representative of the detected energy.
A conventional ultrasound machine 100, operating under the control of a processor 102 such as a microprocessor, receives and processes the resulting data from the scan head 105. The processor 102 typically reads program instruction statements and/or data from a program storage device 101 such as read-only memory (ROM). The ultrasound machine 100 displays a 2D image of the tissue volume being scanned, e.g., on a video display terminal 110, a film camera, or other hard copy device (not shown). Movement of the scan head 105 results in different 2D views of the tissue volume being presented.
Additional background information can be found in, e.g., Fractional Moving Blood Volume: Estimation with Power Doppler US, at pages 183 et seq. of the October 1995 edition of RADIOLOGY, which is incorporated herein by reference, and in the references cited therein.